linux-kernel - Re: [PATCH] usb: gadget: udc: renesas_usb3: Add null pointer check in usb3_irq_epc_pipe0

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Message-ID: <2025052142-waking-monopoly-37a6@gregkh>
Date: Wed, 21 May 2025 13:02:22 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Wentao Liang <vulab@...as.ac.cn>
Cc: u.kleine-koenig@...libre.com, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] usb: gadget: udc: renesas_usb3: Add null pointer check
 in usb3_irq_epc_pipe0_setup()

On Wed, May 14, 2025 at 05:50:53PM +0800, Wentao Liang wrote:
> The function usb3_irq_epc_pipe0_setup() calls the function
> usb3_get_request(), but does not check its return value which
> is a null pointer if the function fails. This can result in a
> null pointer dereference.
> 
> Add a null pointer check for usb3_get_request() to avoid null
> pointer dereference when the function fails.
> 
> Fixes: 746bfe63bba3 ("usb: gadget: renesas_usb3: add support for Renesas USB3.0 peripheral controller")
> Cc: stable@...r.kernel.org # v4.5
> Signed-off-by: Wentao Liang <vulab@...as.ac.cn>
> ---
>  drivers/usb/gadget/udc/renesas_usb3.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/renesas_usb3.c b/drivers/usb/gadget/udc/renesas_usb3.c
> index fce5c41d9f29..51f2dd8cbf91 100644
> --- a/drivers/usb/gadget/udc/renesas_usb3.c
> +++ b/drivers/usb/gadget/udc/renesas_usb3.c
> @@ -1920,11 +1920,13 @@ static void usb3_irq_epc_pipe0_setup(struct renesas_usb3 *usb3)
>  {
>  	struct usb_ctrlrequest ctrl;
>  	struct renesas_usb3_ep *usb3_ep = usb3_get_ep(usb3, 0);
> +	struct renesas_usb3_request *usb3_req = usb3_get_request(usb3_ep);
>  
>  	/* Call giveback function if previous transfer is not completed */
> +	if (!usb3_req)
> +		return;

Why is this check below the comment?  Shouldn't it be above it?

>  	if (usb3_ep->started)
> -		usb3_request_done(usb3_ep, usb3_get_request(usb3_ep),
> -				  -ECONNRESET);
> +		usb3_request_done(usb3_ep, usb3_req, -ECONNRESET);
>  
>  	usb3_p0_con_clear_buffer(usb3);
>  	usb3_get_setup_data(usb3, &ctrl);
> -- 
> 2.42.0.windows.2

How was this tested?

thanks,

greg k-h